#
#   Example 3
#

from plex import *

letter = Range("AZaz")
digit = Range("09")
name = letter + Rep(letter | digit)
number = Rep1(digit)
space = Any(" \t\n")
comment = Str("{") + Rep(AnyBut("}")) + Str("}")

resword = Str("if", "then", "else", "end")

lexicon = Lexicon([
    (name,            'ident'),
    (number,          'int'),
    (resword,         TEXT),
    (Any("+-*/=<>"),  TEXT),
    (space | comment, IGNORE)
])

filename = "example3.in"
f = open(filename, "r")
scanner = Scanner(lexicon, f, filename)
while 1:
    token = scanner.read()
    print token
    if token[0] is None:
        break


